Currents arising from two 'fine heated Platinum Wires. 953 



current of l'OOO amp. were used as an inclinometer. The 

 respective curves correspond to distances apart of the wires 

 equal to 0*170 cm., 0'595 cm., and 2*480 cm. The first, 



SO 135 130 £25 270 'i\ 5 350 



INCLINATION OF PLAr^£ OT WISES TO HORIZONTAL (D£GRE£S) 



that corresponding to a distance of 0*170 cm., shows very 

 considerable symmetry in the various quadrants, and is the 

 type of calibration curve obtained in the paper already 

 referred to*. The curve corresponding to a distance apart 

 of the wires equal to 595 cm., shows that for all inclina- 

 tions, the resulting deflexion is very small. The zero 

 deflexion corresponding to rotation through 90° has been 

 already discussed. At other inclinations, the zero or at most 

 very small deflexion probably arises owing to the movable 

 wire being subjected to the effect of a downward convection 

 stream originating in the central wire, the effect of a higher 

 temperature of such downward convection stream being- 

 counterbalanced by the smaller velocity of the stream as 

 tbe plane of the wires is rotated from the initial horizontal 

 position. The effect of such downward convection stream is 

 clearly shown in the remaining curve of fig. 1, corre- 

 sponding to a distance apart of the wires equal to 2*180 cm. 

 It is clear that as the inclination of the plane of the wires to 

 the horizontal is increased from zero, the deflexion is 

 initially positive, corresponding to an increase of the 



* Proc. Phvs. Soc. vol. xxxii. part v. pp. 291-314 (1920), 

 Phil, Mag. S. 6. Vol, 12. No. 252. Dec. 1921. 3 B 



